Oxford, Air Navigation
The Pressure Altimeter: DGCA Air Navigation questions
An altimeter is a barometer with a height scale. Sealed aneroid capsules expand as static pressure falls, and a linkage turns that movement into feet. The scale assumes the International Standard Atmosphere, so a real day leaves errors to allow for.
Expect 7 short questions on the parts of the instrument, the ISA figures behind its scale, its errors, blocked static vents and what QFE and QNH show on the ground. Exam sessions have asked 1 of these altimeter items.
The usual trap is direction. Flying from high pressure to low with the subscale unchanged makes the altimeter over-read, so you are lower than it shows. Colder than standard air does the same.
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Question 1 of 5
The diagram below shows a simple altimeter. The parts labelled A, B, C and D are:
Question 2 of 5
In the International Standard Atmosphere, the mean sea level pressure is ......., the lapse rate of temperature ....... between MSL and ....... and is isothermal up to ....... The numbers missing are:
Question 3 of 5
An aircraft taking off from an airfield with QNH set on the altimeter has both static vents blocked by ice. As the aircraft climbs away the altimeter will:
Question 4 of 5
When flying from low pressure to high pressure, without resetting the altimeter datum, the barometric error of an altimeter will cause the instrument to:
Question 5 of 5
The errors affecting the pressure altimeter are:
2 more questions in this chapter
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